[comp.sys.ibm.pc.misc] Numerical Methods for Poynomial Root Finding?

blombardi@x102c.ess.harris.com (Bob Lombardi 44139) (01/12/91)

Greetings,

Now that I've decided to buy Borland's Turbo Pascal Numerical Methods
Toolbox, I find that they have discontinued the product.  (I have noticed
this phenomenon before, and it indeed is a law of nature, derived from 
electro-weak theory.) :):)

Does anyone have it that would like to sell it?

If not, can anyone point me to a reference that explains the Laguerre
algorithm that they use, so that I can write my own?  The Laguerre 
algorithm finds all roots of polynomials from entered coefficients.  
I have what I thought was a good collection of post-calculus math books,
but none have anything by this name.  

Lacking that (I get three strikes, don't I?) can anyone refer me to 
source code in Pascal, BASIC, or FORTRAN that finds the roots of 
polynomials?  I can usually translate the other two languages into TP
if I get code in them. 

Since I've posted this to several groups, I'd appreciate reply by email
to save net bandwidth. 



Thanks,
Bob



Bob Lombardi WB4EHS     >>>>>>> Internet: blombardi@x102c.ess.harris.com
M/S 102-4826, Harris Corp GASD, P.O. Box 94000, Melbourne, FL 32902   
Hobbies:  ********  on hold thanks to being a gradual student in EE ******
aspiring classical pianist.   Professional: electrical engineer, writer.

price@helios.unl.edu (Chad Price) (01/13/91)

blombardi@x102c.ess.harris.com (Bob Lombardi 44139) writes:


>If not, can anyone point me to a reference that explains the Laguerre
>algorithm that they use, so that I can write my own?  The Laguerre 
>algorithm finds all roots of polynomials from entered coefficients.  
>I have what I thought was a good collection of post-calculus math books,
>but none have anything by this name.  

See page 279 of Numerical Recipes in C by Press,Flannery,Teukolsky, and
Vetterlingg (1988, Cambridge Univ Press) for explanation and source
code. There is also a Fortran version of the book.

chad price
price@fergvax.unl.edu

bobo@hpcvra.cv.hp.com. (Bob O'Donnell) (01/15/91)

The book "Numerical Recipes" by Press, Flannery, Teukolsky and Vetterling
includes a section on Laguerre's Method for finding roots of polynomials.
The book is published in three versions, one for C, one for Fortran and
one for Pascal.

kchen@Apple.COM (Kok Chen) (01/16/91)

jkenyon@css.itd.umich.edu (Jim Kenyon) writes:

>Just received a copy of "Numerical Recipies" by Press, Flannery, et al 
>and couldn't be happier -- strongly suggest this book for anyone with
>numerically intensive computing needs!


Don't know if this has been mentioned yet; but Acton's book "Numerical
Methods that (almost) Work" spends a large amount of paper discussing 
root solving methods.  Highly recommended if you want to learn such
techniques, instead of just using canned routines.

And, if anyone wants to plow through a few inches of manuscript, 
Wilkinson's "The Algebraic Eigenvalue Problem" has some good hints
on root solving too.

Regards,

Kok Chen, AA6TY				kchen@apple.com
Apple Computer, Inc.